The present invention relates generally to techniques for measuring, modifying, analyzing, imaging objects and surfaces having reentrant or other structural elements. The invention relates to SPM probes whose characteristic shape and radius may be obtained by dynamic motion of the tip end.
The present invention uses variant forms of scanning probe microscopy and employing nanotubes and particularly carbon nanotubes which may be catalyzed and grown by Chemical Vapor Deposition (CVD) using sites made of iron, molybdenum, cobalt, nickel, ruthenium, zinc and oxides thereof. Further these nanotubes may have materials such as copper, silver, platinum, palladium, gold, indium, niobium and other suitable materials including materials that exhibit non-linear optical behavior such as second, third and n harmonic EMF emissions and/or fluorescence deposited internally and/or at the probe tip and may be welded or joined together to make assembled coaxial nanotube structures with varying diameters. In nanotubes the attogram quantities of materials require much lower melting points than in bulk e.g. copper goes to under 800° C. and silver with a bulk melting point of 961.93° C. melts at less than 700° C. both temperatures being compatible with carbon nanotubes.
In present techniques for SPM sidewall profiling, measurement or modification probe tips are used which limit the size of reentrant recesses to 60 nm or greater. Further the necessary large end diameter of present probes for sidewall profiling mean that resolution of common (non-reentrant) surfaces is low in resolution (limited by the probe tip diameter to 10 times or more poorer lateral resolution than that obtained with conventional probe tips) and the extreme delicacy of such probes and their cost limit the speed of common surface scans well below those of conventional sharp probes. Semiconductor processes and other applications in material and biological applications demand sidewall ability for recesses sized below 60 nm with very large depth to width ratios. None of the present techniques offer the ability to measure double reentrant structures. Further such present tips are easily broken and suffer rapid wear in recesses which approach their working diameters. Breakage and aging in any tip used is something very desirable to monitor in situ which is difficult or impossible for present systems. It has also always been desirable to detect the materials being scanned and to be able to transport to or from target sites volumes of material to partially remove and/or partially deposit thereon.
Present techniques for scanning and scanning probe microscopes (SPM) using nanotube tip ends also are limited in general by the flexibility of nanotubes and their common tendency to adhere (stick) to surfaces due to Van Der Waals attraction which in particular causes artifacts in the detection system of the SPM and especially on surfaces having modest to extreme slopes. The latter effect has limited the application of such nanotubes despite their otherwise excellent properties of strength, hardness, minimum wall angle over very large length to diameter ratios and small end diameters of 2 nanometers or less. Finally the variability, alignment and mounting problems of conventional AFM, TUNA and similar cantilever enabled SPMs are a major obstacle to a broad adoption of multi-mode SPM measurement on the factory floor.
It is an object of this invention to provide a means by which reentrant recesses as small as or smaller than 50 nm may be imaged, modified and measured. Another object is to use obdurate nanotubes as the principal tip material to provide diamond like wear characteristics. It is a further purpose of this invention to show a means whereby doubly reentrant structures may be imaged, modified and measured. It is yet another object of this invention to provide a means whereby photons may be collected or delivered by the probe tip for measurement, modification or material transformation, addition or subtraction of the target surface or volume. Further it is the purpose of this invention to provide for sections of nanotube of similar or different diameters welded to create a probe with multiple resonant and structural characteristics. It is yet another purpose of this invention to provide a means of phase and amplitude differential actuation of reentrant tips such that complex non-symmetrical resonance of the probe (nanotube) tip may be obtained. Another purpose is to provide for reentrant measurement using electron methods such as STM, TUNA and other related methods. A further purpose is to provide a means for calibrating such measurements. Yet another purpose is to provide a means for adding or removing material from surfaces, and interior volumes and measuring the mass of such material. Also using the latter mass to determine the density and identify the material or its constituents. Further it is desirable to provide a method to effectively use nanotubes with varying stiffness and end radius. It is another purpose of this invention to overcome general use problems with nanotubes in which the local Van Der Waals force causes the nanotubes to adhere to the probed surface and interfere with the SPM surface data collection. It is a further purpose of this invention to provide various methods for measuring the surface or volume interaction of nanotubes due to the change induced in their resonance in one or more axis of motion, said resonance due to mechanical, electric, or electromagnetic means. It is also a purpose of this invention to provide a SPM surface approach and/or surface measure using nanotubes and a means to drive resonant or non-resonant motion in said nanotubes due to electric, or electromagnetic fields in conjunction with other common methods or as the principal means of such approach or measurement. In conjunction with the latter means it is also a purpose of this invention to provide a means for determining and monitoring the resonant frequency of a nanotube structure by use of a reflected signal.
The following detailed description together with the accompanying drawings will provide a better understanding of the nature and advantages of the present invention.
Materials within the nanotube matrix in process or in situ as attached to or grown onto an appropriate SPM such as metals drawn to the ends of the nanotube increase electrical coupling and photon coupling to structural detectors or emitters. Further such material can be used to adjust the resonant frequency of the nanotube oscillators used in sidewall sensing.